Conditional Sentences

Introduction

In this lecture our concern is not with subtleties in the logical or semantic properties of conditional sentences, but with the tight connection between the meanings of English conditional sentences and features of their grammatical form.

In a conditional sentence, there are two parts, (1) the antecedent = the protasis, and (2) the consequent = the apodosis. In general I will refer to them simply as "P" and "Q", from the logician's tradition of representing material implication as "P implies Q".

Most of the examples we consider will be of the form "if P, Q", but actually there are numerous ways of expressing the meanings that get expressed in English conditional sentences. Here are some examples:

1. "If you come closer, you'll be able to see the parade."
   (the form we'll mainly be considering)
2. "Unless you come closer you won't be able to see the parade."
   (If you don't stand closer, you won't be able to see the parade)
3. "Do you like it? It's yours!"
   (If you like it, it's yours)
4. "Come here and I'll give you a kiss."
   (If you come here, I'll give you a kiss.)
5. "Criticize him the slightest bit and he starts crying."
   (If you criticize him the slightest bit, he starts crying.)
6. "Get out of here or I'll call the police."
   (If you don't get out of here I'll call the police.)
7. "Anyone who does that deserves to be punished."
   (If anyone does that, they deserve to be punished.)
8. "With his hat on he would look older."
   (If he had his hat on, he would look older.)
9. "Otherwise, I wouldn't be here."
   (If things were not the way they are, I wouldn't be here.)

Our main examples will be of type (1) above, marked by the introducer "if", and with the antecedent or subordinate clause preceding the consequent or main clause. (Hence, "if P,Q".)

Dependencies in Conditional Clauses

It is common to think of "if" in English as a kind of conjunction, and to think of the meaning of a conditional sentence as a straightfoward product of the meanings of its component clauses. In the simplest way of thinking of this, the truth of a conditional sentence is a product of the truth values of its individual clauses, according to a truth-table that holds the full sentence to be true unless the P part is true while the Q part is false.

This implies, of course, that each of the parts of a conditional sentence could stand on its own, and could have its truth determined independently of the other. Consider the following sentences:

1. If it rains in California, everybody always gets gloomy.
2. If I touched Jimmy, he would burst into tears. Is it true that "it rains in California"? Yes. Is it true that "everybody always gets gloomy"? No. Therefore, sentence (1) is false.

But of course that line of reasoning doesn't make sense. We have to understand the phrase "in California" as taking the entire sentence in its scope, just as we understand "everbody" as taking in Californians who experience rain, which is not at all what "everybody" means in a self-standing sentence. Sentence (1) is undoubtedly false, but not for the reason worked out from the truth-table for material implication.

Is it true that "I touched Jimmy"? No. I wouldn't think of it. Is it true that "he would burst into tears"? I can't answer that, since a sentence with a conditional modal can't be evaluated on its own. Assuming, for the same of argument, that the second clause is either true or false, then sentence (2) is true. But we know, of course, that the truth of this sentence, as we usually understand it, cannot be determined in that way.

The point is, of course, that the subtle ways in which we understand the actual conditional sentences that get used in everyday talk involve detailed consideration of the actual grammatical form of the sentences themselves. 

Types of Meanings of Conditional Sentences

Eve Sweetser, in From Etymology to Pragmatics has classified conditional semantics according to the three domains she speaks of in that book, the content domain, the epistemic domain, and the speech act domain. Content-based conditionals are understood by relating the content of the two clauses to each other. A typical way in which content conditionals can be understood is for the "P" clause to identify a situation which causes or automatically results in the state of affairs signalled by the "Q" clause. This is the case for

• If you drop it, it will break.
• If you say that again, I'll slap you.
• If it rains, we'll cancel the picnic.

Epistemic conditionals are understood as expressions of the reasoning process. If the state of affairs represented by the "P" clause turns out to be true, then we are licensed to believe what we are told in the "Q" clause. Thus:

• If their lights are on, the Wilsons are home from their vacation.
• If the streets are wet, it rained last night.
• If she wins, she's been practicing in secret.

And speech act conditionals are understood as pre-posing to a speech act a "P" clause that identifies the situation which got the speaker to provide the speech act. Thus:

• If you're hungry, I could find something for you in the fridge.
• If you leave before I see you again, have a good time.
• If what I said offended you, I apologize.

We will see, in comparing the verbal forms of conditional sentences, that some combinations can only have the epistemic interpretation, others can have either an epistemic or a content interpretation. I have not explored the formal conditions for being a speech-act conditional. 

Verbal Forms

A major descriptive problem that grammarians have to face in dealing with English conditional sentences involves the complex system of compatibility relations between the two parts of a conditional sentence. That is, certain verbal forms occurring in the antecedent clause of a conditional sentence are compatible only with certain other verbal forms in the consequent clause. Some examples of compatible combinations are these:

• If she opens it, they will escape.
• If she opened it, they would escape.
• If she had opened it, they would have escaped.
• If she opened it, they escaped.

Some examples of incompatible (or at least difficult-to-contextualize) combinations are the following:

• *If she'll open it, they had escaped.
• *If she were here, I'll be happy.
• *If she opens it, she had misunderstood my message.

What we need for this set of facts is some set of general principles according to which these acceptability judgments, and the accompanying interpretations, can get explained.

The tools we need for stating these principles include the following:

• First, we need to have a vocabulary for describing the various verbal forms which enter into the compatibility relations just mentioned;
• second, we need to speak of something I will refer to as "epistemic stance" - the speaker's stance on the reality of the proposition expressed in the antecedent clause;
• third, we will need to notice that some sentences give expression to what we can call the "interlocutors' interest" - the speaker's view that of the alternatives recognized by a conditional sentence, one is looked on as matching the speaker's or the hearer's interest (this will be modified below); and
• fourth, we will need to notice features of "polarity" - the difference between positive polarity and negative polarity.

Describing the selection of verbal forms in English conditional sentences is made complex by the facts that some of the relevant categories are not identifiable with particular morphemes or particular individual grammatical notions, but with complexes of these. What this means is that we will have to give different names to forms that have the same, or almost the same, superficial appearance. Furthermore, in discussing the categories we need, it is necessary to keep in mind the difference between "Time" (which we take as a semantic notion) and "Tense" (a grammatical notion).

The names of the verbal-form categories we will use are these:

• present
  the form which, in the copula, results in is, am, are and in the non-modal verbs uses the sibilant suffix to express third-person-singular agreement (walks)
• past
  the form which, in the copula, results in was, were and otherwise, in the "regular" cases, the simple past-tense inflection (walked)
• future
  the expression of future meaning with the modal will followed by the unmarked infinitive
• present subjunctive
  this form is the same as the past- tense form, except that, in some dialects (perhaps especially in the U.S.) there is a single form for the copula: were
• past subjunctive
  this form is the same as the pluperfect form (had gone, etc.), except that in colloquial English we also find a more complex form (had've gone, etc.), and in colloquial American English we find a form identical to what I will call "conditional perfect": would have gone.
• conditional
  this form is constructed with would or could plus the unmarked infinitive (would go, etc).
• conditional perfect
  this form is constructed with would or could plus the perfect infinitive (would have gone, etc.)

In general, "perfect aspect" and "progressive aspect" can coexist with most of these forms and contribute their own meanings. In other words, in describing a conditional antecedent, the form "if he has seen her" will be simply classified as "present" for present purposes. 

http://www1.icsi.berkeley.edu/~kay/bcg/lec07.html